1H-Imidazolium, 3-ethyl-1-methyl-, C11-13-branched alkylbenzenesulfonates

Toxicity to aquatic algae and cyanobacteria

Description of key information

The 72 hour EC50 (based on growth rate) was calculated as 176.49 mg/l. In accordance with EU CLP criteria, it can be concluded that the test substance is not a short-term or a chronic toxin to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

176.49 mg/L

EC10 or NOEC for freshwater algae:

0.68 mg/L

EC10 or NOEC for marine water algae:

2.02 mg/L

Additional information

A study was conducted on the registered substance to determine the short-term toxicity of the substance to aquatic algae.

The short-term toxicity of the test substance to aqautic algae was determined in accordance with the OECD Guideline for Testing of Chemicals 201. The effect of EMI-DBS test item was assessed on algal growth using the unicellular green alga Pseudokirchneriella subcapitata (Selenastrum capricornutum), over an exposure period of 72 hours.

A significant toxic response was observed during the preliminary range-finding test, therefore six test concentrations in a geometric series with a separation factor of 3.2 and one untreated control were tested in the main experiment.

The nominal concentrations of test item used in the main experiment were: 0.3; 1.0; 3.1; 9.8; 31.3 and 100.0 mg/L. The corresponding measured geometric mean test item concentrations were: 0.21; 0.68; 2.02; 6.62; 23.63 and 79.31 mg/L.

As the measured concentrations deviated more that 20 per cent from the nominal in most cases, biological results are based on measured geometric mean concentrations. The test design included three replicates at each test concentration and six replicates for the untreated controls. Statistical comparisons of biomass, average specific growth rates and yield in control and in treated groups were carried out using analysis of variance (ANOVA) and Bonferroni t-Test (a = 0.05) by TOXSTAT software.

The ErC50, EbC50 and EyC50 values of the test item and their confidence limits were calculated using Probit analysis by TOXSTAT software. With respect to the inhibitory effect of the test item, the 0-72 h average specific growth rates were significantly different from that of the control group in the examined concentration range of 2.02 - 79.31 mg/L (measured), therefore the NOEC was determined as 0.68 mg/L (measured) and LOEC was determined as 2.02 mg/L (measured). The 0-72 h yield and areas were significantly different from that of the control group in the examined concentration range of 0.68 - 79.31 mg/L (measured), so the NOEC was determined as 0.21 mg/L (measured) and the LOEC was determined as 0.68 mg/L (measured). The 72 hour EC50 (based on growth rate) was calculated as 176.49 mg/l. In accordance with EU CLP criteria, it can be concluded that the test substance is not a short-term or a chronic toxin to aquatic algae.